PURPOSE: To provide a titled pig iron which maintains the spheroidization rate with ordinary graphite spheroidization treatment and is free from deterioration in material quality by specifying C and Si in the pig iron to a prescribed content and controlling the total sum of Mn, P, S and other trace elements, O, N and gray cast iron rates and the blowholes in the gray cast iron part.
CONSTITUTION: A titled pig iron is the pig iron contg. C and Si in a hypereutectic range and having the components contg., by weight, ≥0.30% Si, ≤0.10% Mn, ≤0.020% P, ≤0.010% S, ≤0.050% total sum of other trace elements and ≤20ppm both O and N. The ratio of the gray cast iron part at the fracture of the mold pig iron (gray cast iron rate) of said pig iron is ≥30% and the pig iron has no blowholes on the surface and the inside. If such pig iron is used, the graphite spheroidization rate is high and the high graphite spheroidization rate is maintained down to the central part, thus resulting in an increased average number of graphite particles. The abnormal number of graphite is hardly generated in the central part where the solidification is slowest.
SUZUKI ATSUNOBU
SUZUKI KIYOSHI
TAKAHASHI HIROO
